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Probing of pore in the Chara gymnophylla K + channel by blocking cations and by streaming potential measurements
Author(s) -
Pottosin Igor I.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80070-w
Subject(s) - chara , chemistry , channel (broadcasting) , ion , blocking (statistics) , analytical chemistry (journal) , biophysics , chromatography , botany , electrical engineering , biology , organic chemistry , statistics , mathematics , engineering
The current—voltage (I–V) relationship of single K + channels present in the Chara gymnophylla droplet membrane was studied. The channel presumably contains large mouths at both pore ends which are sufficiently wide to accomodate TEA + as evidenced by internal and external TEA + blockade. The voltage dependence of blockade by external Cs + and Na + reveals the multi‐ion occupancy of the channel. The value of streaming potential (4.0 mV/osmol) measured in the Chara K + channel indicates that the channel contains up to nine water molecules in the narrow region. It is concluded that the length of this region is around 28 Å.